Evaluation of a New Field Measurement Method for Arsenic in Drinking Water Samples

The recently lowered arsenic maximum contaminant level will require numerous U.S. water utilities and agencies to monitor and treat for arsenic. This paper describes a new method that measures arsenic in drinking water samples by generating arsine gas from the water and detecting the arsine using a paper-tape instrument. Laboratory tests indicated the method is capable of accurately detecting arsenic in water samples at the microgram per liter level (method detection limit of 0.5?μg/L and practical quantification limit of 2.5?μg/L). The only significant interferences were hydrogen sulfide and antimony. Using the paper-tape instrument, it is also possible to detect As(III) and As(V) that have been separated by either selective arsine generation or ion exchange. While the method proved accurate in the lab, difficulties were encountered during preliminary field testing on 18 different real samples. This technique of converting aqueous arsenic to arsine gas for analysis shows great promise, but the method needs to be refined for use in the field.